Reflective Air-Gap Insulated Duct for Higher R-Value
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Solution Overview
Problem
Existing HVAC ducts face challenges in achieving high thermal resistance (R-value) without increasing the amount of bulk insulation, which is costly and cumbersome to manufacture, especially when used in unconditioned spaces where higher R-values are required.
Innovation Solution
A flexible insulated duct design featuring a uniformly-spaced reflective insulation system with a low emissivity surface and a spacer system, such as a star-shaped spiral helix, expandable lattice blanket, or lattice cord and post assembly, creating a uniform air gap between the liner and jacket to enhance R-value independently of bulk insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the amount of bulk insulation is increased to achieve higher R-value, then thermal resistance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the physical parameters of the insulation system by introducing an air gap of specific thickness (0.125 to 0.250 inches) between the liner and outer jacket. This parameter change creates a reflective insulation effect that increases thermal resistance without adding bulk insulation material, thereby improving R-value while avoiding the manufacturing complexity associated with handling and installing thick insulation layers.
Solution Approach 2:
The patent transitions from a one-dimensional insulation approach (bulk insulation thickness) to a two-dimensional approach by incorporating an air gap dimension between the liner and outer jacket. This dimensional change enables reflective insulation to function, providing thermal resistance through radiation reflection rather than solely through conduction resistance, thus achieving higher R-values without increased bulk insulation.
2Temperature
If the amount of bulk insulation is increased to achieve higher R-value, then thermal resistance is improved, but weight increases
Solution Approach 1:
The patent modifies the insulation system parameters by creating an air gap that enables reflective insulation to function effectively. This parameter change allows the duct to achieve higher thermal resistance using minimal bulk insulation material, significantly reducing the weight compared to conventional ducts that rely on thick layers of bulk insulation to achieve the same R-value.
3Temperature
If the amount of bulk insulation is increased to achieve higher R-value, then thermal resistance is improved, but packaging and installation difficulty increase
Solution Approach 1:
The patent changes the insulation configuration by introducing an air gap, which allows the duct to achieve high R-values with minimal bulk insulation. This parameter change results in a more compact duct structure that is easier to package, transport, and install compared to conventional ducts with thick bulk insulation layers, while still meeting or exceeding required thermal resistance values for unconditioned space applications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design provides improved thermal resistance, reduced material costs, lighter weight, and easier packaging and installation, allowing for more efficient air handling and reduced shipping and storage needs while maintaining or exceeding R-values of standard ducts.
Implementation Method 1
a reflective insulation system surrounding the liner and between the liner and the jacket. The reflective insulation system includes a low emissivity reflective surface
Implementation Method 2
at least one spacer system positioned between the liner and the jacket, the spacer system creating a generally uniform air gap between an outer surface of the liner and the inner surface of the jacket
Data Source
AI summary
A flexible air duct contains a uniformly-spaced reflective insulation system, with or without bulk insulation, a liner, and an outer jacket that would allow a reduced amount or no amount of bulk insulation to be used to obtain a desired R-value insulation. The flexible air duct can be used to move conditioned air to one or more desired locations.